The present invention is related to an improved cell for measuring the electrical conductivity and ion content of vapor, and, more particularly, to a cell of this type in which the accuracy of the measurements is increased by reducing or eliminating certain leakage currents.
A typical prior art cell of the above type includes an enclosed volume or chamber within a housing into which a vapor, such as moist air, is introduced. Mounted within the volume is a plurality of metal plates suspended therewithin an adjacent, spaced, parallel relationship. There are two sets of plates.
In a typical cell, each plate in the first plate set, constituting every other plate, is suspended from, and is electrically continuous with, a pair of metal rods or robust wires. One rod passes through each plate of the first set at or near an upper corner thereof, while the other rod passes through each plate at or near a diametric lower corner. The adjacent plates constituting the second plate set are suspended from, and are electrically continuous with, another pair of rods, one of which passes through each plate of the second set at or near an opposite upper corner and the other of which passes through the plates at or near a diametric lower corner.
The foregoing assemblage of plates is suspended within the chamber by mounting the opposite ends of the rods to insulators which are also located in the chamber. The rods are electrically continuous with measuring facilities outside the chamber. After the vapor has been introduced into the chamber, the measuring facilities apply appropriate voltage and current to the rods and the plates and analyze the response of the assemblage to these applied stimuli so as to derive a measurement of the electrical conductivity and ion content of the vapor.
In the past, it has been noticed that the vapor or its constituents at times condense on the insulators. Where the vapor is water vapor or moist air, the condensate on the insulators constitutes a thin water film. Condensates on the insulators permit leakage currents to flow across the insulators. Leakage currents across the insulators affect the measuring facilities so as to obscure or render inaccurate the measurements of the conductivity or ion content of the vapor. Further, if a vapor is to be subjected to successive tests using plates of varying sizes or numbers, insulators of the same size must be used in each test so that the same errors are present in each test to permit meaningful comparisons of the results thereof.